So-called camless valve driving devices, which eliminate cams for valve driving and instead employ electromagnetic driving or hydraulic driving of the valve in order to enhance freedom of engine control, are viewed as promising. Such technology is disclosed in Japanese Patent Publication No. 7-62442 and in Japanese Patent No. 3019275 and the valve opening and closing timing and lift amount of the device can be set freely.
In such a device, high fluid pressure is developed that is sufficient to lift the valve by the necessary amount in opposition to the valve spring, and this pressure is applied to the valve to perform the desired lifting. However, when a large amount of energy is required to apply high fluid pressure to the valve for valve driving the valve driving loss is increased, and there is the disadvantage that reduced fuel efficiency may result.